Because of adverse effects associated with the administration of whole cell vaccine, development of improved pertussis vaccines is of high priority. The Food and Drug Administration is responsible for ensuring that these vaccines are both safe and effective. We have therefore developed a battery of assays to test the safety and potency of these vaccines. These assays test the vaccines for purity, lack of toxicity, lack of the ability to revert to a toxic form, and immunogenicity. These tests have been applied to four lots of acellular pertussis vaccines being evaluated in large scall efficacy trials in Sweden and Italy, as well as other vaccines currently under IND and PLA status. Efforts are underway to develop and standardize potency and toxicity tests which can be used as reliable measures of the reproducibility of manufacturers of these vaccines. A standardized ELISA is currently being developed which will measure the immune response in mice to the four antigens found in acellular pertussis vaccines. These antigens are filamentous hemagglultinin, pertussis toxoid, 69 kDa protein, and fimbriae. The preparation of suitable control reagents for the tests are underway. A pilot study to define optimal immunization schedules in order to prepare mouse hyperimmune reference serum is complete and the immunization of mice is in progress.